media: platform: stm32: Add check for clk_enable()

commit f883f34b upstream.

Add check for the return value of clk_enable() to gurantee the success.

Fixes: 002e8f0d ("media: stm32-dma2d: STM32 DMA2D driver")
Cc: stable@vger.kernel.org
Signed-off-by: Jiasheng Jiang <jiashengjiangcool@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>